HeadsUp: Starting tomorrow the last outbound 1AX/BX, 31AX/BX, and 38AX/BX trips currently scheduled for 7 pm will b https://t.co/kiUprCjHxg (More: 16 in last 24 hours)

Central Subway Construction Update 3/1/19

Friday, March 1, 2019 - 12:00am

Thank you for your interest in the Central Subway Project, which is a significant project in the history of San Francisco's public transportation network. This project is the first underground line to link the north and south corridors of the city, and will provide a direct connection to major retail, sporting and cultural venues while efficiently transporting people to jobs, educational opportunities and other amenities throughout San Francisco.

This is an exciting time as the San Francisco Municipal Transportation Agency's | Central Subway team works to construct a vital transportation link that, when open in 2019, will improve connectivity for the city. SFMTA Director Ed Reiskin speaks at the reopening of Stockton Street to vehicular traffic on Friday, March 22nd. Central Subway | Project Advancement

March 1 through March 10, 2019

This notice provides a construction update and a look ahead for what to expect in the areas where we are building four new stations along the alignment. You’ll find information about work activities, traffic and transportation impacts taking place over the next two weeks at SoMa, Yerba Buena/Moscone, Union Square and Chinatown.

Construction schedules, bus routes, and stop locations are subject to change due to unforeseen conditions. Signs will be posted at affected stops to advise of service changes.

Our thanks go out to the businesses, residents, shoppers, commuters, and all those who are touched by the Project, for their continued engagement as we work to extend the city's public transportation system.

The Central Subway Team

Rebar for track foundations continues to be installed in the southbound tunnel just south of the Union Square/Market Street Station platform, inside the S-curve under the Market Street subway. Surface Station, Trackwork and Systems Work along 4th Street between Bryant Street and King Street includes construction of a surface station between Bryant Street and Brannan Street. The construction team is upgrading utilities and trackwork on 4th Street between the tunnel portal at Bryant Street and the connection with the existing light rail system at King Street.

Sidewalk and pavement renovation work is underway at 4th and Bryant.  This work may affect vehicular and pedestrian traffic through that part of the intersection.  Construction of the 4th and Brannan surface station platform is ongoing.  Some lane closures may also occur at night.  Regular day shift hours are from 7am to 4pm.  Tracks diverge along the southbound side of the Chinatown Station track crossover cavern, just south of the station platform. Workers clean this section of the northbound tunnel just south of the Market Street S-curve, following the installation of utility conduits. Overview

  • Night work on 4th Street between King and Bryant
  • Street and sidewalk restoration


What: Night utility work on 4th between King and Bryant
Time: 8 p.m. - 5:00 a.m.
When: Monday to Saturday
Where: 4th Street between King and Bryant
What: Utility installation and street restoration work

What: Street and sidewalk restoration
Time: 7 a.m. - 5:30 p.m.
When: Monday to Saturday
Where: 4th Street between King and Bryant

What to expect

  • Work may involve saw-cutting, potholing and jack-hammering on the roadway and sidewalk
  • Sidewalk access may be limited
  • Access will remain open for pedestrians and businesses 
  • Parking and Traffic Impact
    • Partial lane closures on 4th Street between Townsend and King streets.
    • Parking will be unavailable in the work area on both sides of 4th Street.
    • Two lanes of traffic open on 4th Street, one on the east side and one on the west.
    • Traffic impacts are in effect 24 hours a day.
  • Muni Impact
    • No scheduled impacts at this time.

A supervisor watches an associate on a lift inside a large ventilation structure being constructed atop the Yerba Buena/Moscone Station headhouse. Yerba Buena | Moscone Station

4th Street from Howard to Folsom

Work along 4th Street between Howard Street and Folsom Street consists of construction of the underground Yerba Buena | Moscone Station. The cut and cover method involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

Water main replacement work continues at night at 4th and Howard streets.  Work hours are 9 p.m. to 5 a.m.  Eastbound traffic on Folsom may be impacted.  Three through lanes are in place southbound 4th Street. Westbound traffic on Howard Street may be impacted.

A vast array of interior elements including glass paneling and utility conduits are being installed on the concourse level. A massive concrete form stands as part of work to construct the wall at the south end of the main station entrance structure. Overview

  • Water main replacement work at 4th and Howard
  • Installation of headhouse and station interior elements


What: Water main replacement work
Time: 9pm - 5am
When: Monday to Friday
Where: 4th and Howard Street intersections.

What: Installation of headhouse and station interior elements
Time:  5am - 3:30pm
When: Monday to Friday
Where: 4th Street between Howard Street and Folsom Street What to expect

  • Clementina Street is closed for traffic and pedestrians through to 4th Street
  • The sidewalk on the west side of 4th Street is closed south of Howard
  • Parking and Traffic Impact
    • Two lanes of traffic open on the east side of 4th Street, may be reduced to one lane at night between 9 pm and 5 am Monday through Friday.
  • Muni Impact
    • No scheduled impacts at this time

    SFMTA Director Ed Reiskin and a host of community and business representatives cut the ribbon to reopen Stockton to vehicular traffic between Geary and Ellis. Union Square | Market Street Station

    The construction of an underground Union Square|Market Street Station uses the cut and cover method known as a "top-down" or "bottom-up" approach and involves construction of a box frame structure within a trench excavation that is subsequently backfilled.

    Stockton Street has been reopened to both traffic and transit between Geary and Ellis. This allows the 8, 8AX, 8BX, and 91 OWL bus routes to return to their previous alignments, with the 30 and 45 returning later this year.  One lane on the south side of Ellis Street is open at all times for eastbound traffic.  Parking garage access is open on north side of Ellis Street.

    The installation of waterproofing, structural elements, and concrete at the southeast corner of the Union Square Garage continues.  There will be a continued presence of vehicles and equipment as work at this location continues.  Installation of internal structural elements and utilities is ongoing under Stockton Street as well as the northeast corner of Stockton and O'Farrell.

    Two men on the platform level pass tools to each other while installing portions of a future elevator mechanism. A crew pours concrete on to fill a last few panels of sidewalk following the reopening of Stockton between Geary and Ellis. Overview

    • Installation of internal structural elements and temporary bracing
    • Union Square Garage (north station entrance) structural installation


    For all activities, construction hours may be 24 hours a day, Monday to Saturday, Sunday work may be required What to expect

    • Sidewalk access may be limited at times
    • Parking and Traffic Impact
      • The 8, 8AX, 8BX, and 91 OWL bus routes have returned to their previous alignments outbound on Stockton Street south of Geary, however the 30 and 45 bus routes require additional infrastructure to be constructed and will be able to traverse this stretch of Stockton later this year.
    • Muni Impact
      • No scheduled impacts at this time.

    Carpenters have built concrete forms for a portion of a large structure at the south end of the Chinatown Station platform. Chinatown Station The construction of Chinatown Station used the sequential excavation method (SEM), providing a high degree of flexibility and control over ground conditions, thereby greatly reducing the risks of construction. This method of tunnel construction is used worldwide for small to large openings in a variety of ground types ranging from rock to soil.  Excavation of the Chinatown Station site was completed in February 2018.

    Current activities include construction of the north and south platform caverns, cross-cut cavern, track crossover cavern, and interior structural elements of the station headhouse.  The sidewalk along the west side of Stockton between Washington and mid-block toward Clay has temporarily been closed to facilitate utility upgrade work.  A pedestrian walkway is open on the north side of Washington connecting Trenton and Stockton.  Work to build the north egress shaft on Stockton south of Jackson is underway. Carpenters build sections of concrete forms on the level above the Chinatown Station concourse, inside the headhouse. A 30 Stockton bus passes signage placed to aid pedestrians about a sidewalk closure facilitating utility upgrade work. Overview

    • Construction of structural elements inside the station headhouse
    • Construction of stem walls and track slabs for Platform Cavern
    • Construction of North Emergency Egress Shaft on Stockton Street


    What: Headhouse structural elements, stem walls, track slabs, north emergency egress shaft, and utility vault upgrades
    Time: 24 hours
    When: Monday to Saturday
    Where: Stockton Street and Washington Street What to expect

    • A portion of the sidewalk along the west side of Stockton adjacent to the Chinatown Station worksite has temporarily been closed south of Washington to facilitate utility upgrade work.
    • Sidewalk access may be limited at times
    • Parking and Traffic Impact
      • No parking on both sides of Stockton Street between Washington Street and Jackson Street
      • One lane of traffic on both sides of Stockton Street between Washington Street and Jackson Street
      • Stockton Street:
        • sidewalk is open on the west side between Washington Street mid-block toward Clay
      • Washington Street:
        • remains closed between Stockton Street and Trenton Street, except to pedestrians
        • is converted into a two-way street between Powell Street and the construction zone
    • Muni Impact
      • No scheduled impacts at this time.

    Connecting People. Connecting Communities.

    Contact Us: If you have questions about construction or the Central Subway Project you can email us at central.subway@sfmta.com or leave a message at (415) 701-4371.

    For More Information: The Central Subway team posts frequent project updates on a variety of social media outlets. To find out more about the project and construction progress, follow us on Facebook, Twitter, or Flickr.

    Construction schedules are subject to change.